1. Field of the Invention
The present invention relates generally to power window modules and more specifically to window replacement assemblies for use in a rear cab opening of a truck.
2. Description of the Prior Art
In typical pickup truck cabs, as mass produced by various manufacturers, the rear of the cab has a generally trapezoidal shaped window opening into which a solid, immovable piece of glass is fitted. A window gasket secures the glass n that opening.
Consumers, however, have found it desirable to be able to open the rear window of the cab to improve ventilation in the cab. Some automobile accessory manufacturers have attempted to meet this demand for windows that can be opened by providing substitute window assemblies. These substitute assemblies house split, horizontally sliding windows. To install such windows, the original glass pane provided by the manufacturer is removed with the gasket. After the gasket is separated from the original glass pane, the substitute sliding window assembly is inserted in place of the original window in the gasket.
Typically, in such prior art sliding window assemblies, the area within the window frame is divided into three panes; the middle pane is adapted to slide past at least one of the other two panes. However, such substitute windows are operated manually and therefore have several shortcomings. The window is located substantially behind the driver and out of the driver's field of vision. Thus, the driver cannot safely open or close the window while driving.
Other prior art substitute modular windows use electro-mechanical systems to fully retract a single rear window pane into a frame disposed within the track cab. Although these power window modules represent a significant improvement over the unpowered, earlier prior art designs, they also have certain shortcomings.
One such prior power window module is disclosed in U.S. Pat. No. 4,119,341 to Cook. U.S. Pat. No. 4,119,341 uses a motor powered gear and lever arm system for raising and lowering a single glass pane. Because of the substantial weight of the glass pane, the motor required for providing the mechanical power to raise and lower the window must be quite powerful. Such motors are expensive and noisy.
A second prior art power window is disclosed in U.S. Pat. No. 4,671,013 to Friese et al. U.S. Pat. No. 4,671,013 discloses a power window module wherein a complicated pulley system driven by a motor raises and lowers one pane of glass. Using this pulley system allows the use of quieter, less powerful motors. However, the unit still has several shortcomings. Its bulk, which makes installation difficult, and the expense of manufacturing the unit inhibit consumer acceptance of these types of designs.
Finally, a prior art power window module disclosed in U.S. Pat. Application Ser. No. 07/100,126 to Friese et al. represents an improvement on the prior designs. This application discloses a power window module which overcomes some of the shortcomings of U.S. Pat. No. 4,671,013 by replacing the pulley system with a pair of slotted tapes which are driven by a motor to raise and lower a single glass pane. This module, however, shares several shortcomings with U.S. Pat. No. 4,671,013 in that the module is difficult to install because of its bulk and is expensive to manufacture. Also, as in the other prior art power window modules, if they fail with the window in the open position, the window cannot be readily closed until the unit is repaired.
All three prior art power window modules discussed above share an additional limitation. They cannot be installed into a truck cab if the rear cab wall is not nearly vertical or if the truck has a second row of seats such as those found in some "king cabs."